GitHub - CodingDock/headlong: High-performance Contract ABI and RLP for Ethereum

Contract ABI and Recursive Length Prefix made easy for the JVM. Everything heavily optimized for maximum throughput (ABI function call encoding up to 500x faster than a popular competitor. One function init plus one encode up to 50x faster ("sam(bytes,bool,uint256[])", openjdk 12.0.1)).

ABI spec: https://solidity.readthedocs.io/en/latest/abi-spec.html

RLP spec: https://github.com/ethereum/wiki/wiki/RLP

SHA-256 (headlong-1.4.7.jar): a5041b9b0030e49f6674dda42010130777d472ad9237445f877be992630307fd

Usage

ABI codec

Encoding

Function f = new Function("baz(uint32,bool)"); // canonicalizes and parses any signature automatically
Function f2 = Function.fromJson("{\"name\": \"foo\", \"type\": \"function\", \"inputs\": [ {\"name\": \"complex_nums\", \"type\": \"tuple[]\", \"components\": [ {\"name\": \"real\", \"type\": \"decimal\"}, {\"name\": \"imaginary\", \"type\": \"decimal\"} ]} ]}");

Tuple args = new Tuple(69L, true);

// Two equivalent styles:
ByteBuffer one = f.encodeCall(args);
ByteBuffer two = f.encodeCallWithArgs(69L, true);

System.out.println(Function.formatCall(one.array())); // a multi-line hex representation
System.out.println(f.decodeCall((ByteBuffer) two.flip()).equals(args));

Decoding

Function getUfixedAndString = new Function("gogo((fixed[],int8)[1][][5])", "(ufixed,string)");

Tuple decoded = getUfixedAndString.decodeReturn(
        FastHex.decode(
                "0000000000000000000000000000000000000000000000000000000000000045"
              + "0000000000000000000000000000000000000000000000000000000000000020"
              + "0000000000000000000000000000000000000000000000000000000000000004"
              + "7730307400000000000000000000000000000000000000000000000000000000"
        )
);
        
System.out.println(decoded.equals(new Tuple(new BigDecimal(BigInteger.valueOf(69L), 18), "w00t")));

RLP codec

// for an example class Student
public Student(byte[] rlp) throws DecodeException {
    RLPIterator iter = RLP_STRICT.sequenceIterator(rlp);
    
    this.name = iter.next().asString(UTF_8);
    this.gpa = iter.next().asFloat();
    this.publicKey = iter.next().data();
    this.balance = new BigDecimal(iter.next().asBigInt(), iter.next().asInt());
}

@Override
public Object[] toObjectArray() {
    return new Object[] {
            Strings.decode(name, UTF_8),
            FloatingPoint.toBytes(gpa),
            publicKey,
            balance.unscaledValue().toByteArray(),
            Integers.toBytes(balance.scale())
    };
}

@Override
public byte[] toRLP() {
    return RLPEncoder.encodeSequentially(toObjectArray());
}

Also includes a fast hex codec and an optimized Keccak implementation.

Build

Now available in Maven Central Repository.

Or build locally:

Clone the project and install to your local maven repository using gradle publishToMavenLocal or mvn install. Then you can use one of these:

implementation 'com.esaulpaugh:headlong:1.4.8-SNAPSHOT'

<dependency>
    <groupId>com.esaulpaugh</groupId>
    <artifactId>headlong</artifactId>
    <version>1.4.8-SNAPSHOT</version>
</dependency>

Alternatively:

Run gradle build or gradle jar which output to /build/libs
Use mvn package which outputs to /target
Add headlong as a project dependency

Depends on gson. Tests should take less than one minute to run. Test packages require junit and spongycastle. Jar size is ~115 KB as of 06/21/19.

See the wiki for more, such as TupleTypes, packed encoding, RLP Lists, and RLP Object Notation: https://github.com/esaulpaugh/headlong/wiki

Licensed under Apache 2.0 terms